Centerless grinding machine



Dec. 3, 1946.

W. MELIN CENTERLESS' GRINDING MACHINE Filed March l0, 1945 2 Sheets-Sheet 1 Gtorneg Dec. 3, 1946. ,-w. MELIN.

y CENTERLESS GRINDING MACHINE Filed March' lO, 1945 -2 Sheets-Sheet 2 Snventor Patented 3,

UNITED STATE s PATENT OFFICE cENTanLns's Gammo William Melin, Grand Rapids, Mich. application mmh 1o, ms, serial No. 582,029

8 Claims. (Cl. 51-95) The present invention relates to grinding machines, and more particularhr to a machine for grinding and nishing rotary cutting tools to their true circular size.

The primary object of the invention is to provide a support for presenting round work to the grinding wheel of a grinding machine in such a manner that the work will'be ground to its true circular shape and size with respect to the center thereof.

Another object of the invention is to provide a device of the above-mentioned type in which the work is rotated at a speed different than the speed of the grinding wheel while `*being ground and finished so that thel peripheral surfaces thereof will be finished to circular size and shape more accurately and with a; comparatively high 'degree of precision finish and polish.

Another object of the invention is to provide a machine of the type set forth in the preceding paragraph which is particularly adapted for grinding and nishing the 'relief surfaces of ro- Vtary cutting tools such as end mills and. drills so that said rotary tool will have all of its peripheral surfaces spaced equidistant from the center of the tool and in true concentricity therewith.

Another object of the invention is to provide a machine for grinding the relief edges of end mills and other rotary cutting tools such as twist drills and reamers in which the support therefor, in addition to supporting and rotating the tool relative to the grinding wheel is movable to feed the rotary cutting tool axially of the peripheral surface of the grinding wheel and thereby grind and finish said relief edge through the entire length or pitch of the cutting tool.

Another object of the' invention is to provide a machine tool in which the grinding wheel is driven by an independent source of power to permit-the grinding wheel to be moved laterally toward and away from the work and to provide the rotary work support-with a separate source y of power so that the support may be fed axially with respect to the grinding wheel and thereby grind and finish the lands and cutting portion of the rotary tool without necessitating resetting or shifting of the tool during grinding and ilnishing thereof.

Another obiect of the invention is to provide a grinding machine for rotary tools of the abovementioned type in which the work roll may be manually moved away from the supporting rolls to permit the insertion and removal of the cuti ting tool after the peripheral edge or land thereof has been ground and ilnished.

, are undercut as at Il to mate with the under- .finishing machine embodying the invention; i

Figure 2 is a side elevational view of the grindving machine showing portions thereof Abroken away to illustrate various structural details of the work support; l

Figure'3 is an end elevational View of the grinding machine showing the work and supporting rolls' thereof so as to properly present the work to the peripheral surface of the grinding machine; Y

Figure 4 is a vertical cross-sectional view taken on the zig-zag line l-I of Figure 1 and looking in the direction of the arrows to lllustrate the motor support and the flexible drivefo the work roller; f Y

Figure 5 is a vertical cross-sectional view of the work roll and work supporting rolls to illustrate their position and arrangement relative to one another; and a Figure 6 is a top pla-n view of a modified grindv ing machine structure illustrating a slightly different grinding wheel arrangement for grinding internal diameters of various work pieces.

In the drawings, attention is directed to Fig-4 ures 1 to 5 inclusive wherein the referencecharacter l will generally be employed to designate a machine bed or base oi.' a grinding machine and said vbed consists ofa rectangular casting having a top wall B, front and rear walls 1 and` I l and end walls l connected thereto. Extending longitudinally of the top wall 6 is a pair yof spaced guide ribs 9 undercut as at Ill to provide slide ways for accommodating a slide Ii. The slide Il is provided with a longitudinal groove I! on the underside thereof for slidably receiving said slide ways l `and the walls of said slot I2 cut portion of the guide ribs 9 and thereby retain said, slide in slidable engagement with the bed 5.

Journaled in a bearing boss formed integral with the front wall 1 and top wall I ofthe machine bed or base I is anoperating shaft il having one end projecting through`tfhe said wall 'I and fitted with an operating crank l secured ,I

rectly beneath a slot formed in the top wall 8 v of the machine bed or base and is provided with a gear wheel. 2l keyed or otherwise affixed thereto. Secured to the underside of the slide II and within the groove 20 therein is -a rack bar 22 heid in place by longitudinally spaced anchoring bolts 23. The teeth 24 of the rack bar 22 arein mesh with the teeth on the gear wheel 2l so that rotation of the shaft I4 by the crank II` will cause said gear teeth to drivingly engage said rack and feed the slide longitudinally along the machine base or bed 5.

Mounted on the rear wall I8 of the machine base 5 is a motor and grinding wheel supporting bracket 25 of angle formation having one of its extensions bolted as at 26 togthe rear wall I8 of the machine base or otherwise fastened in place, while the other extension 21 extends rearwardly and provides a platform or support for an adjustable slide 28. The platform extension` 21 is provided with a dove-tailed slot 29 for receiving the dove-tailed slide rib 30 on the underside of the adjustable slide 21. An adjusting screw Il has one of its ends mounted for rotation in a bearing plate 32 bolted to the angle bracket 25 by means of bolts or the like as at 34. A threaded bore A: 14 is formed in the'slide 2B for receiving the threaded end of the screw shaft 3| so that rotation of said shaft as by means of a knurled hand piece 35 affixed on said shaft will feed the slde 21 forwardly and rearwardly of the machine base or frame 5. The screw shaft 3| is provided with an annular lenlarged portion I9 in abutting relationship with the bearing plate 32 to prevent endwise movement of the shaft.

Secured to the slide 28 is an electric motor 38 l ends of a drive shaft 15. Mounted on the ldrive* having its base 31 fastened to the slide 21 by means of bolts or machine screws 38.- i The arma- .ture shaft 3S of the motor 36 projects a considerable`distan`ce beyond the motor frameI and said motor shaft is adapted to rotatably. support a grinding wheel 40 the hub of which as at 4I is slidably Vreceived on said armature shaft and held in place by means of a retaining nut 4I.

Abracket plate 44 is mounted on the slide Il and said bracket plate is bolted in place by means of machine screws or the like as at 45. -Formed integral with the bracketplate 44.v is anupstanding supporting arm 46 and said arm iscut away as at 41 at one side thereof to provide sufficient room for the work pieces to be ground.

Mounted in theupper end of the upwardly extending arm 48 is a pair of' horizontal shafts 4B secured in place by locking pins 48 and the ends of said shaftsv48- are reduced as at lll and are fitted with inner race members 5I having grooves for receiving anti-friction balls 52; An outer ball bearing race member A54 encircles the inner ball bearingrace member Il and fitted-on the outer ball bearing race member 541s a worlr'engaging roller 55. It will thus be seen that the work engaging rollers 56 on each side of the upwar .y extending arm 46 and on each end ofthe spaced shafts l48 are freely rotatable for engag- .ing the work and supportingthe same during grinding. l

Formed directly -in front of the vertically extending arm,46 is'an enlarged boss 58 having a` transverse bore 51 through which extends a pivot shaft member 58. A work roller frame 58 is pivoted to the enlarged bore Se and is provided at each side with downwardly extending arms te which straddle the enlarged boss 56 and receive the free ends of the shaft lle in openings Bl therein. An `anchoring pin 82 is passed transversely through the downwardly depending extension 60 andthe shaft 58 to prevent endwise movement of thework roller frame 5e relative to the shaft 58. A pairsof spaced upwardly extending arms 83 and B4 are formed on the work roller frame 5e and said arms are bent slightly as indicated ln Figure 2 so that the upper end of the arm $3 as at 85 will be slightly shorter than the upper end 68 with the end portions in parallel relation-and provided with suitable bores 81 and 68 respectively for receiving ball bearing' race members having inner andy outer bearing races 89 and 10 respectively. Anti-friction ball bearings 1l are mounted between the inner and outer race members @Band 10 and the inner race member 68 is provided with a bore'13 for receiving the shaft between the ends of the arms l5 and 66 is a roller 1B held in place by means of a set screw 11 an'dsaid roller is provided with a spaced annular groove 18 adjacent each end thereof for receiving resilient work engaging means 19. The

' work engaging means 19 are adapted to fit snugly within the groove 18 and may be formed of rubber or a similar resilient material. It is noted thatthe drive shaft .1I is slightly angled to the horizontal and one end thereof is extended beyond the upwardlyvdirected arm 65 to facilitate a driving connection therewith. frame 59 is provided with a coil spring anchoring pin e0 over which is fastened one end of a coil spring 82 while the opposite end of said spring ls hooked in an eye Il secured to the upstanding arm 46 of the bracket plate 44.. It will thus be seen that the spaced upstanding arms I3 and B4 of the work roller'frame le will be urged toward the work supporting rollers Bl so as to drivinsly engage the shank S of an end mill M in position with the nuted portion of the end mill M presented'to the peripheralsurface of the grinding wheel 40. A handle 84 is secured-to the work roll frame 69 so. thatthe operator may depress thelever 84 and rock the work roll supporting frame le on its pivot pin 5l and retract the resilient work engaging rings 1e from engagemenibwith the work and thereby permit another piece of work to be inserted and similarly removed after grinding.- A'work engaging stop is provided for the shank S of the end mill and includes a bracket arm 85 having a' base as at le bolted to the slide Il by means oLmachine screws or the like as at el. The upper end el of the bracket arm Il I is provided with a transverse bore le for receiving a work engaging bar el)A which is adlustably held in place by means of a set screw 9| threaded in an opening e2 in the free end of the bracketarm Il so that its inner end engages` and clamps the work engaging support l in place.

Abracket 92 having a flanged portion "is bolted' to the slide Il by means of bolts or thelike as at 94 and said bracket ve2 extendsupwardly from the slide Il and` is so disposed as to pro-v videa platform 95 at the upperend. thereof'for supporting an electric motor et. The base 21 of the electric motor is fastened in place by means of bolts or machine screws 80 having their threaded ends anchored in' suitable openings lin the platform QI. Alsoymounte'd on the slide II adjacent one end thereof is a bracket plate 9e having a pair of upstanding arms me and said bracket The work roller plate l! is fastened to the slide b y anchoring bolts |0| extending through thebase' and into the top surface of the slide The upper ends vof the parallel arms i are provided with bearing bosses Il! in which is iournaledi a rotary shaft |03 in alignment with the work roll drive shaft Mounted on the shaft |03 is a pulley i which has its hub Il! disposed between the bearing bosses |03 and said pulley is provided with a pulley groove |06 of V-formation for receiving a drive belt |01. The V-drive belt II'I is trained over a pulley |08 mounted on the end of the armature shaft |09 of the electric motor ll so that rotation of the armature shaft will impart rotary motion to the drive shaft ill. A ilexible tubular coupling memberv Ill has one of its ends fitted over the work roll drive shaft 'I5 and held in place by a clamp I surrounding -the end of said' tubular coupling so `as to clampingly engage the same rand cause said coupling end to hand piece ll is rotated to adjust and position be connected'to the work roll drive shaft 1I. v

The other end of the coupling I Il is iltted over the drive shaft |03 and is similarly provided with' a clamping ring lil for establishing a drive connection with the shaft l". It will thus be seen that energization of the motor 98 will cause the shafts 'Il and |03 as well as the yielding ring-like elements I0 on the work roll 'I6 to be rotated so as to impart rotation to the work piece while the saine is held against the supporting roll Il.

A stop plate III is bolted to the rear wall il of the'machine bed I by means of machine screws I I l and said stop plate is provided at its upper end with a boss II'I having -a threaded opening for receivingan adjusting screw III. 'I'he ad- .iusting screw may be held in place by a lock nut Il! threaded thereon and engaging the boss Ill and a wrench-engaging head I2. formed on the end of the stop screw llt to facilitate adjustment thereof. The free end of the adjusting screw III is adapted to engage a stop esurface |2| formed on the side wall of the bracket 52 to limit the longitudinal movement of the slide Il and the endwise feed of the end mill relative to the grinding wheel Il.

In' themodifled form of the invention in Figure 6, the grinding machine structure and fixture is identical to the work support shown in the form of the' invention in Figures 1 to 5 inclusive with the exception that the slide 28 for supporting the motor 3B is provided with ,an extension ill formed integral therewith,with the outer end of said extension enlarged as at ISI to provide a bearing boss for a short shaft I 32. The armature shaft 39 is provided with a pulley |33 over which is trained afdrive belt IM and said belt l l is adapted to drive a pulley ,Ill mounted on one end of the short shaft |82 and thereby rotate the same. The opposite end of the short shaft |32 is threaded for a portion of its length and provided with an enlarged portion ISI forming a collar for engaging and providing a limiting stop for the grinding wheel |31. A nut III is threaded on the end of the short shaft |32 tos'ecrely clamp the grinding wheel |51 in place. i

It is noted that the work roll Il is rotated in the opposite direction to the grinding wheel lll `so that the cutting surface of the tool such as an end mill. reamer or twist drill being ground will be given a hlshly polished nish to facili'- tate the passage of chips ofthe cutting tool.

In operation the motors and Il are started to causethe grinding wheel Il and work rollv Ill and prolong the life `eries in driving engagement with said shank as indicated in Figure 5. After the work piece has been placed between the work supporting rolls 5l and work roll 1l, the hand crahk I8 is rotated so as to feed the slide I| to and fro with the fiuted portion of the end mill M presented to the grinding wheel I0. Rotation of the work roll 'I6 feeds the shank S of the end mill M into contactual engagement with the work stop!! to thereby prevent the end mili from becoming displaced during the grinding operation. After the end mill has been ground to the required circular size, the lever BI is depressed and the end ymill removed from between the work supporting rollers 55.

As shown in Figure 6, a work piece W isasupported between the work supporting rolls Ilr'carried by the upper end ofthe bracketfarm II and said work piece is likewise engagedr by the work roll Il with the yielding rubber rings thereonas at 'I9 .in driving engagement with a portion of said work piece. When it is intended to grind the internal surface of a piece of work, the grinding maohineshown in Figures 1 to 5 may be easily converted by substituting the slide as at 2l having an extension |30 and grinding wheel |31 at the end thereof in lieu of the slide 2l, motor 3B and grinding wheel shown and described in Figures 1 .to 5 inclusive. To transpose the grinding machine to the .type shown in Figure 6 it is simply necessary to rotate the knurled handpi'ece ll to displace the slide 2l in either case and replace the same with the slide 2! as desired.

It is to be understood that the forms of the invention herewith shown and described are to be taken as preferredembodiments of the invention and that various changes may be made in the shape, size and arrangementof parts without departing Afrom the spirit of the invention or .the scope of the subioined claims.

What I claim is: 1. A grinding machine, comprising a base, a

slide mounted for movement thereon, a grinding wheel carried by the hase, work supporting rolls mounted on the slide to receive a work piece, a work driving roll mounted between the work supporting rolls and on'set therefrom, a motor and speed-reducing mechanism mounted on the slide, and a exible coupling connection between the speed-reducing mechanism and work driving roll, said motor being yieldingly connected to the f projecting above said slide. a pair of spaced apart work supporting rolls mounted verticallyy one above the other on the slide. a frame Pivotedto said slide adjacent said work supporting rolls, a work driving roll mounted in the frame for movement toward and away from said work supporting rolls in an approximately horizontal direction for gripping a work piece therebetween at three cir- .eumierentiaily spaced points, drive means carried by .the slide for driving said work driving roll. 'and means for yieldingly urgingsaid work A driving roll toward said work supporting rolls.

8. A centerless grinder, comprising a base, a

slide movably mounted on said base, a grindingv wheel supported rearwardly o! said base and projecting above said slide. a pair oi spaced apart at one end o! said work supporting and driving rolls for engaging said work piece.

- tion for, slipping a work piece therebetween at work supporting rolls mounted vertically one above theother on the slide, a frame pivotedto said slide adjacent said worky suppOrting rolls, a work driving roll mounted in the frame for movement toward and away from said' work supporting rolls in an approximately horizontal direction for gripping a work piece therebetween at three circumierentia'lly spaced points, drive meins carried by the slide for driving said work driving roll, and means for yieldingly urging said work driving roll toward saidy work supporting rolls,` said work driving r'oll being .tilted to the horizontal to feed said work against a stop carried by the slide.

4; A centerless grinder, comprising a base, a slide movably mounted on said base, a grinding wheel supported rearwardly of said base and projecting above said slide. a pair oi spaced apart work supporting rollsA mounted vertically one above the other on the slide,` a frame pivoted to said slide adjacent said work supporting rolls, a work driving roll mounted in .the frame for movement toward and away from said work support'.-

' ing rolls in an approximately horizontal direc# ,tion for gripping' a work piece therebetween at three circumi'erentially spaced points, drive rneans carried by the slide for driving said work driving roll, means tor yieldingly urging said work driving roll toward said work supporting roilsrand work stop means carried by the slide three circumierentially spaced points, drive means carried by the slide for driving said work driving roll, means tor yieldingly urging said work driving roll toward said work supporting' rolls, and a stop adjacent oneend oi said work supporting and driving rolls.' said work driving roll being inclined to feed the end of said work into engagement with said stop.

6. A centerless grinder,'comprising a base, a slide movably mounted on said base. a grinding wheel supported rearwardly oi! said base and projecting above said slide, a pair of spaced apart work supporting rolls mountedI vertically one above the other on .the slide, a frame pivoted to said slide adjacent said work supporting rolls, a work driving roll mounted in the frame' for movement toward and away from said work supporting rolls in an approximately horizontal di rection for gripping a work piece therebetween at three circumierentially spaced points, drive means carried bythe' slide for driving said work driving roll, means for yieldingly urging said work driving roll toward said work supporting rolls, a handle connected to said work driving roll supporting frame to move .the work driving roll away from said work supporting roll, and a stop means carried by the slide engageable with adjustable stop means on the base for limiting sliding movement or said slide relative .to the base. A

y WILLIAM 

